The new European X-ray Free-Electron Laser is the first X-ray free-electron laser capable of delivering X-ray pulses with a megahertz inter-pulse spacing, more than four orders of magnitude higher than previously possible. However, to date, it has been unclear whether it would indeed be possible to measure high-quality diffraction data at megahertz pulse repetition rates. Here, we show that high-quality structures can indeed be obtained using currently available operating conditions at the European XFEL. We present two complete data sets, one from the well-known model system lysozyme and the other from a so far unknown complex of a β-lactamase from K. pneumoniae involved in antibiotic resistance. This result opens up megahertz serial femtosecond crystallography (SFX) as a tool for reliable structure determination, substrate screening and the efficient measurement of the evolution and dynamics of molecular structures using megahertz repetition rate pulses available at this new class of X-ray laser source.

Microfluidic approaches to nanomaterial synthesis provide an effective means of making high quality products, with exquisite control over electronic, optical, and structural properties. Furthermore, microfluidic reactors integrating analytics and real‐time reaction control have recently emerged as powerful tools in automating materials exploration and reaction parameter mapping, with a rapidity and efficiency that is inaccessible to traditional flask‐based methods. Herein, the recent innovations in the microfluidic synthesis of photonic nanoparticles, whose varied luminescent and plasmonic properties have found great application in the biomedical and optoelectronic sciences, are presented. Special attention is placed on the achievements and promise of microfluidic approaches in automated multidimensional reaction parameter screening employing in situ optical characterization. In an extended outlook, the future of the field is explored, looking toward the integration of smart control systems and machine learning algorithms, and demonstrating how maximal positive impact can be achieved. Far from degrading or replacing the ingenuity of the experimentalist, these tools will provide new powers of exploration, augmenting the discovery process. Further, through automation and miniaturization, it is expected that such approaches will fulfill the moral imperative of maximizing the benefit derived from the natural resources consumed in conducting research.

Abstract. Ice nucleation in the atmosphere is the precursor to important processes that determine cloud properties and lifetime. Computational models that are used to predict weather and project future climate changes require parameterizations of both homogeneous nucleation (i.e. in pure water) and heterogeneous nucleation (i.e. catalysed by ice-nucleating particles, INPs). Microfluidic systems have gained momentum as a tool for obtaining such parameterizations and gaining insight into the stochastic and deterministic contributions to ice nucleation. To overcome the shortcomings of polydimethylsiloxane (PDMS) microfluidic devices with regard to temperature uncertainty and droplet instability due to continuous water adsorption by PDMS, we have developed a new instrument: the Microfluidic Ice Nuclei Counter Zürich (MINCZ). In MINCZ, droplets with a diameter of 75 µm are generated using a PDMS chip, and hundreds of these droplets are then stored in fluoropolymer tubing that is relatively impermeable to water and solvents. Droplets within the tubing are cooled in an ethanol bath. We validate MINCZ by measuring the homogeneous freezing temperatures of water droplets and the heterogeneous freezing temperatures of aqueous suspensions containing microcline, a common and effective INP in the atmosphere. We obtain results with a high accuracy of 0.2 K in measured droplet temperature. Pure water droplets with a diameter of 75 µm freeze at a median temperature of 237.3 K with a standard deviation of 0.1 K. Additionally, we perform several freeze–thaw cycles. In the future, MINCZ will be used to investigate the freezing behaviour of INPs, motivated by a need for better-constrained parameterizations of ice nucleation in weather and climate models, wherein the presence or absence of ice influences cloud optical properties and precipitation formation.